This application claims the benefit of Korean Application Nos. 98-31697, filed Aug. 4, 1998 and 98-46240, filed Oct. 30, 1998, in the Korean Patent Office, the disclosures of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to the field of error correction, and more particularly, to an interleaving method and circuit which can be applied to a high density recording medium having a high definition digital versatile disc (HD-DVD) format and by which high-speed searching can be achieved.
2. Description of the Related Art
There is a recent trend toward an increase in the capacity of data recordable on an optical disc. This trend allows storage of various information in order to record and reproduce a corresponding large amount of data to provide good picture quality and excellent sound quality, and in order to play a sufficient role as a peripheral apparatus of a computer.
To do this, an optical disc has a storage capacity of about 4.7 Gbyte due to the development of an initial compact disc (CD) having a storage capacity of about 600 Mbyte into a DVD-format disc (DVD). The storage capacity of about 4.7 Gbyte allows reproduction of about 135 minutes of data with a picture quality of the Moving Picture Expert Group (MPEG)-2 and a sound quality of audio coding (AC)-3.
However, recent trends are demanding the industrialization of high definition televisions (HDTVs) and a picture quality of a HDTV level. Thus, a recording medium having a storage capacity for a greater amount of data is required to meet the demand for HDTV-level picture quality. An HD-DVD format disc (HD-DVD) has been developed to achieve the above-described demand.
Storage of about 15 Gbyte data increased by approximately 3.28 times from the about 4.7 Gbyte of data capable of being stored in a general DVD must be enabled to continuously reproduce pictures and sounds having levels corresponding to the picture quality and sound quality of HDTVs for about 130 minutes. The HD-DVD allows an increase in the capacity of data recorded on a disc having a size such as that of a DVD-ROM (read only memory) by reducing the actual lengths of a recorded bits.
However, in this case, the number of errors generated upon detection of data in a pickup unit of an optical recording and reproducing apparatus is increased, and the size of data loss due to generation of a small scratch on a disc is much larger as compared to the general DVD. This data loss can be compensated for by an error correction technique which has a great effect on the amount of user recorded data and the reliability of user data upon recording and reproduction, according to how the error correction technique is applied. Therefore, when an error correction method applied to the general DVD is applied to an HD-DVD without change, the reliability of reproduced data is greatly degraded.
A format for an error correction block used in a DVD-ROM, as an example of a DVD, includes 208 rows of 182 bytes as shown in FIG. 1. In the row direction, there are 172 bytes of user data and 10 bytes of inner parity, and in the column direction, there are 16 sectors of 12 bytes and an outer parity of 16 bytes.
This error correction block is interleaved as shown in FIG. 2 to separate adjacent bits from each other and the separated bits are recorded on a disc so that the recorded bits can be error-corrected even when some defects are generated on the disc. That is, 16 bytes of outer parity are arranged such that one byte of outer parity is inserted into the last row of each sector. In this general DVD, only a row-interleaving method is applied in units of an error correction block. This row-interleaving method does not have the error correction capability required by a high density recording medium such as the HD-DVD.
Here, the total error correction block is comprised of 37856 bytes obtained by multiplying 182 bytes by 208 bytes. The range of continuous correctable error in the error correction block is 182 bytesxc3x9716 rows since the outer parity is comprised of 16 bytes. In practice, a sync pattern as well as user data and parity are recorded on a disc, so that the sync pattern must be considered upon calculating the error correction capability. Two sync patterns are inserted in a row. That is, a sync pattern of 64 bits exists in a row of 182 bytes by inserting a sync pattern of 32 bits at intervals of 91 bytes.
Hence, a burst error capable of being corrected in an error correction block for a general DVD-format disc is comprised of 2976 bits which is calculated by 32 bitsxc3x972+(182 bytesxc3x978)xc3x972 since a row-directional line is comprised of 182 bytes and 8 to 16 modulation on the row-directional line must be considered. A burst error capable of being corrected in the entire error correction block is 47616 bits obtained by multiplying 2976 bits by 16 rows. In the DVD disc, the minimum mark length (3T) is 0.4 xcexcm which corresponds to 3 channel bits. Thus, if a correctable length is X, the following equations are obtained:
0.4 xcexcm:3 bit=X xcexcm:47616 bit
X=0.000634 m=6.34 mm
According to the results of the above calculation, the maximum error capable of being corrected in an error correction block for a DVD is comprised of 47616 bits.
In the specification of the DVD, the minimum recordable mark length is 0.4 xcexcm, and the interval (track pitch) between tracks is 0.74 xcexcm. Here, as for error correction capability, error correction can be made even with a scratch of about 6.3 mm in the tangential direction of the disc since an outer parity of 16 bytes exists in the column direction.
Accordingly, in the error correction capability required by a general optical disc, a scratch of about 6.3 mm on the disc in the tangential direction must be able to be corrected. The DVD format disc also requires an error correction capability of this level, and sets the number of bits which can be corrected in an error correction block on the basis of this error correction capability.
In a DVD-ROM, error correction for a scratch of 6.3 mm can be made using an error correction block used in the DVD, but the same error correction cannot be made using the error correction block in an HD-DVD. This is because the scratch of about 6.3 mm affects 47616 bits in a DVD-ROM but the same scratch in the HD-DVD affects information of 156180 bits which is about 3.28 times greater than the 47616 bits. Thus, it is impossible to apply an error correction method used for the general DVD to the HD-DVD without change.
To solve the above problem, it is an object of the present invention to provide an interleaving method for a high density recording medium by which an error correction capability is improved while maintaining compatibility with a DVD format.
It is another object of the present invention to provide an interleaving circuit for a high density recording medium, by which error correction capability can be improved using an error correction code used in a DVD format, and high-speed searching can be made by accessing a desired position in the same amount of time as that for the DVD format.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the first and other objects of the present invention, there is provided an interleaving method for improving the error correction capability of a high density recording medium, the method comprising the steps of: (a) generating first interleaved data by interleaving received data having a predetermined error correction code within error correction blocks; and (b) generating second interleaved data by interleaving the first interleaved data between the error correction blocks in units of a predetermined number of error correction blocks.
To achieve the second and other objects of the present invention, there is provided an interleaving circuit for improving the error correction capacity of a high density recording medium. In this circuit, an intrablock interleaver interleaves received data having a predetermined error correction code within the error correction blocks to output intrablock-interleaved data. An interblock interleaver interleaves the intrablock-interleaved data between the error correction blocks in units of a predetermined number of the error correction blocks to output interblock-interleaved data.